A small portion of the rhodopsin in bovine rod outer segments can be labeled with galactose and fucose in vitro. These sugars are probably added in the outer segment and may play a role in phagocytosis. Various precursors of rhodopsin can be incorporated by both bovine and canine retinas thereby permitting examination of possible defects in dystrophic animals. BIBLIOGRAPHIC REFERENCE: O'Brien, P.J.: Differential effects of puromycin on the incorporation of precursors of rhodopsin in bovine retina. Biochemistry 16: 953-958, 1977.